Four-high roll casting machine

ABSTRACT

A casting machine for continuously producing metal sheet and plate in coils of wide widths, comprising a pair of spaced-apart, parallel casting rolls disposed one above the other and having a feed nozzle discharging molten metal into the space between the revolving rolls. The nozzle is shaped to deliver the molten metal to the proper place for casting, depending upon the angle of the casting machine. The casting rolls are relatively small in diameter, considering their length, in order to make the feed nozzle short and blunt for maximum strength and to reduce the tendency of molten metal to freeze within the nozzle. To prevent the casting rolls from bending outwardly at their midpoints by pressure exerted by the freezing metal which is being reduced in thickness by rolling action of the casting rolls, the latter are backed up by relatively stiff, large-diameter back-up rolls, which press against the casting rolls and prevent them from bending. In the preferred form of the invention, the machine casts downwardly at about a 30* angle, but may be used to cast at any angle from horizontal to vertical.

United States Patent [191 Gilmore FOUR-HIGH ROLL CASTING MACHINE [75] Inventor: Oscar P. Gilmore, Riverside, Calif.

[73] Assignee: S. J. Collins, Riverside, Calif.

[22] Filed: July 20, 1972 [211 App]. No.: 273,471

[52] U.S. Cl. 164/277 [51] Int. Cl B22d 11/06 [58] Field of Search 164/277, 282, 278, 87,

[56] References Cited UNITED STATES PATENTS 1,466,459 8/1923 Perry 72/249 X 1,737,785 12/1929 Coryell 72/249 X 1,878,595 9/1932 Moller 72/235 2,108,752 2/1938 Low 164/277 X 2,128,941 9/1938 I Hudson... 164/277 2,143,336 1/1939 Walton 164/277 2,693,012 11/1954 Harris..... 164/277 X 3,405,757 10/1968 Harvey.... 164/277 X 3,430,683 3/1969 Hood 164/277 X 3,433,047 3/1969 Powell 425/407 X 3,483,915 12/1969 Schneckenburger 164/282 X 3,580,036 5/1971 Zayata 72/249 3,730,254 5/1973 Namy 164/277 r'lllllllllllllt June 18, 1974 Primary Examiner-J. Spencer Overholser Assistant Examiner-John S. Brown Attorney, Agent, or FirmHerbert E. Kidder [57] ABSTRACT A casting machine for continuously producing metal sheet and plate in coils of wide widths, comprising a pair of spaced-apart, parallel casting rolls disposed one above the other and having a feed nozzle discharging molten metal into the space between the revolving rolls. The nozzle is shaped to deliver the molten metal to the proper place for casting, depending upon the angle of the casting machine. The casting rolls are relatively small in diameter, considering their length, in order to make the feed nozzle short and blunt for maximum strength and to reduce the tendency of molten metal to freeze within the nozzle. To prevent the casting rolls from bending outwardly at their midpoints by pressure exerted by the freezing metal which is being reduced in thickness by rolling action of the casting rolls, the latter are backed up by relatively stiff, large-diameter back-up rolls, which press against the casting rolls and prevent them from bending. 1n the preferred form of the invention, the machine casts downwardly at about a 30 angle, but may be used to cast at any angle from horizontal to vertical.

6 Claims, 5 Drawing Figures ,illlllll' llHlllllu.

PRTENTEDJWWW (1817;317-

' sumanfs' v PATENTEDJM 18 m4 sum 5 or 5 Armmmm FOUR-HIGH ROLL CASTING MACHINE BACKGROUND OF THE INVENTION The present invention pertains generally to continu ous casting machines for producing metal sheet or plate in continuous lengths directly from molten metal, and more particularly to that class of machines'in which aluminum alloys and other non-ferrous metals are cast between opposed, water cooled, revolving casting rolls that are spaced apart the same distance as the finished thickness of the cast product. Casting machines of this general'type have been in use for a number of years, and have achieved a considerable degree of commerical success.

However, such machines are limited in the width of strip that they can cast, owing to the separating forces exerted between the casting rolls by the molten metal, which solidifys slightly in back of the nip (the narrowest space between the rolls) before it passes between the casting rolls, thus bending the rolls outwardly and causing the strip to be thicker at the center than it is at the edges. As a result, it has come to be accepted that the maximum width of sheet or plate than can be cast between rolls is about 60 inches. Efforts to minimize bowing of the wide casting rolls by making them larger in diameter and heavier in construction have resulted in greatly increased cost, and have also introduced a whole new sieres of problems in the feed nozzle, owing to the fact that the larger the diameter of the rolls, the smaller the included angle formed by opposing faces of the rolls, and consequently the longer and narrower the tip of the nozzle must be in order to carry the molten metal all the way into the space between the rolls, so that the molten metal contacts the water-cooled roll surfaces just ahead of the narrowest space between the rolls. A long, narrow nozzle is relatively fragile and easily damaged. Moreover, the molten metal loses heat rapidly through the nozzle walls to the relatively cold casting rolls, with the result that the metal tends to freeze in the nozzle, causing damage and shutting down the machine. The nozzle cannot be shortened too much, as this would result in molten metal being discharged into the cold rolls too far ahead of the point of minimum spacing, where it would chill and freeze, and the solidified metal would then be too thick to hotroll" down to the thickness that would pass between the rolls. This would exert a tremendous parting pressure on the rolls, and could not be done.

SUMMARY OF THE INVENTION The primary object of the present invention is to provide a new and improved continuous casting machine of the type wherein molten metal is cast between two spaced-apart, parallel, water-cooled casting rolls, which is capable of casting much wider sheet or plate than has heretofore been possible.

Another object of the invention is to provide a continuous casting machine for casting wide sheet or plate, in which the feed nozzle has substantially the same cross-sectional configuration as in feed nozzles used in conventional machines casting much narrower width sheet or plate.

A further object of the invention is to provide a continuous casting machine of the class described, that casts a sheet or plate downwardly at any angle below the horizontal. It has been found to be advantageous for the sheet to leave the machine on any downward angle for easy, immediate starts with no wasted metal, such as required by any roll casting machine casting at any angle upward from the horizontal. Another advantage of this downward casting is that the machine can be stopped and started up again without damaging the feed nozzle. This is done by shutting off the flow of molten metal into the feed nozzle and allowing the nozzle to drain until empty, after which the machine can be stopped. Restarting is done in the normal manner. In upward casting machines it is impossible to completely drain the feed nozzle, and therefore molten metal freezes within the nozzle, making it necessary to replace the same.

Another object of the invention is to provide a downwardly casting machine having opposed upper and lower casting rolls, in which only the lower roll is driven by the motor powering the machine. Driving power is transmitted through the shaft at one end of the lower casting roll. This arrangement eliminates the need for flexible couplings between the drive motor and the machine, as well as double drive gearing and other attendant mechanisms and hardware that are necessary for the conventional double drive casting machine.

Still a further object of the invention, in one of its aspects, is to provide a continuous casting machine in which the machine is pivotally supported for tilting about the axis of its lower casting roll, and the casting angle can be varied over a wide angle.

The foregoing and other objects and advantages of the invention will become apparent to those skilled in the art from the following detailed description of the preferred embodiment thereof, with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a continuous casting machine embodying the principles of the present invention;

FIG. 2 is a side elevation of the same;

FIG. 3 is an elevational view of the machine, as seen from the exit end thereof;

FIG. 4 is an enlarged fragmentary sectional view taken through the casting rolls and feed nozzle; and

FIG. 5 is a side elevation of another embodiment of the invention, showing the machine in three positions of angular adjustment.

DESCRIPTION OF THE PREFERRED EMBODIMENT In FIGS. 1-4 of the drawings, the casting machine of the present invention is designated in its entirety by the reference numeral 10, and comprises two laterally spaced side frames 12 which hold a first pair of bearing blocks 14 and 15 that rotatably support the ends of casting rolls l6 and 17, and a second pair of bearing blocks 20 and 21 that rotatably support the ends of back-up rolls 22 and 23. The side frames 12 are sup ported on a flat base plate 25, to which they are connected at one corner by pivot pins 27, and the entire structure is held in the inclined position shown in FIGS. 1 and 2 by struts 28. Struts 28 may be solid brace members, or they may be adjustable in length, as in FIG. 5. The angle of inclination of the machine is preferably about 60 degrees to the horizontal, although this is not critical, and any angle might be used from vertical to horizontal.

Each of the side frames 12 comprises a large, steel, U-shaped member 30, the legs of which are keyed and bolted to a straight bar 31, to form a generally rectangular housing having an elongated aperture with parallel side edges 32 that form the ways for bearing blocks 14, 15, and 21. The top ends of the side frames 12 are connected by a transverse bar 33, and the frames are thus tied together at the top by cross bar 33 and at the bottom by base plate 25, to form a rigid cage for the bearing blocks and rolls.

Mounted on the underside of the top leg of U-shaped member is a hydraulic pre-load cylinder 36, which exerts a downward force against the top surface of bearing block 20, causing the top back-up roll 22 to press downwardly along its full length against the top surface of the upper casting roll 16. The downward pressure against the upper casting roll 16 is transferred through its bearing blocks 14 and adjusting wedges 38 to the bearing blocks 15 of lower casting roll 17, and thence by contact with the lower casting roll 17 to bottom back-up roll 23. The pressure against bottom backup roll 23 is transferred by its bearing blocks 21 to the bottom of the legs of side frames 12.

The adjusting wedges 38 (which are shown only schematically in the drawings) space the bearing blocks 14 and 15 apart to determine the spacing between casting rolls 16, 17, which, in turn, determines the thickness of the cast sheet or plate. The wedges 38 are adjusted by any suitable means (not shown) controlled by the operator, who sets the adjustment prior to starting up the machine.

For a wide sheet casting machine (e.g., over 60 inches in width) the casting rolls 16, 17 might be made of steel, with l6-inch diameters and finely ground exterior surfaces. Within each of the rolls 16, 17 are passages (not shown) through which cooling water or any other liquid coolant is circulated to carry away the heat that is absorbed by the rolls from the molten metal. The coolant is then recirculated through a heat exchanger (not shown) which cools it before returning the coolant to the rolls.

The rolls 16, 17 may both be driven by motorsand power transmission systems (not shown) so that their confronting faces move in the same direction at the same predetermined speed. However, the preferred arrangement is to drive only the lower roll 17 by means of a power transmission drive shaft 40, as in FIG. 3; the upper roll 16 being driven by the frictional drag of the cast sheet or plate that is formed by the chilling of the molten metal. The advantage of driving only the one casting roll is that it eliminates the complications and expense of double transmission systems and drive shafts, with a corresponding simplification of the machine and reduction in its cost.

The back-up rolls 22, 23 are made of cast iron or mild steel, and are preferably about twice as large in diameter as the casting rolls 16, 17, so as to give them the maximum rigidity and stiffness to resist bending. Backup rolls 22, 23 are preferably not motor driven, but are frictionally driven by their respective casting rolls l6 and 17.

Molten metal is fed into the space between casting rolls 16, 17 by means of a transversely elongated feed spout 42, which is connected by a plurality of laterally spaced refractory pipes 44 to a head box 46, and launder 48, to the tap-out box of a furnace 52. Feed spout 42 is located on the upwardly facing side of the inclined assembly of rolls, and projects down into the converging space between the casting rolls, as shown in FIGS. 1, 2 and 4. The spout extends laterally for substantially the full width of the rolls 16, 17, and projects down into the region between the rolls almost to the plane AA passing through the axes of the rolls, as seen in FIG. 4.

Feed spout 42 comprises a transversely elongated, open-top channel 54 of refractory material such as Marinite, a proprietary product made of diatomaceous silica, asbestos filler, and hydrated lime, as described in US. Pat. No. 2,326,516. Other ceramic or ceramic-like materials which are inert to the molten metal being cast and are not wetted thereby, might be used in place of Marinite.

The left-hand side of the channel 54, as seen in FIG. 4, is formed by a tapered, wedge-shaped nozzle 56, having an internal passageway that terminates in a narrow, continuous slit 58 extending the full width of the nozzle. The top and bottom surfaces of the nozzle 56 are cylindrically curved to form converging concave sides 60 that conform closely to the curvature of the rolls 16, 17. Nozzle 56 extends into the converging space between the rolls almost to the plane A--A in FIG. 4, and the discharge end of the nozzle is therefore relatively thin. The Marinite blocks forming the feed spout 42 are enclosed between perpendicular brass end plates (not shown) which are also arcuately curved on their top and bottom edges to conform to the rolls 16, 17, and the tip ends of said plates extend all the way in to plane A-A, to serve as dams to confine the molten metal against running out of the ends before it has chilled.

Operation of the continuous casting apparatus is as follows: The work rolls 16, 17 are first opened to a predetermined spacing between them by adjusting the wedges 38, which space the bearing blocks 14, 15 apart againts the pressure exerted by hydraulic pre-load cylinder 36. Feed spout 42 is then inserted into the space between casting rolls 16, 17, and is adjusted to provide a predetermined clearance between the concave sides 60 and the rolls. The flow of coolant is started up through the casting rolls 16, 17, and after preheating the feed spout 42 up to operating temperature, a starting block of the same thickness as the product to be cast is inserted into the space between the rolls from the exit end thereof. Molten metal is then run into the feed spout 42, and discharges into the space between the rolls 16, 17, where it chills and solidifies. At the same time, rolls 16, 17 are caused to start turning. and after expelling the starting block, the machine continues to turn, producing a continuous sheet or plate of metal.

As the molten metal issues from the nozzle 56, it contacts the chilled surfaces of the rolls 16, 17 and solidifies almost immediately. The solidified metal is then carried along by the rolls into the area of plane AA where the space between rolls is at its minimum,, and in the process, compresses and hot-rolls the metal. The pressure of the metal tending to spread the rolls 16, 17 apart is extremely high, and the rolls would tend to bow apart if not restrained by the back-up rolls 22, 23. The back-up rolls bear against the sides of the casting rolls opposite the cast metal, and being much larger in diameter than the casting rolls, they are extremely stiff and unyielding. The casting rolls 16, 17 thus are reinforced and stiffened by the back-up rolls, without having to lose the advantages of their relatively small diameter, which makes for shorter and more rugged feed spouts.

If the total spreading force acting against rolls 16, 17 I the excessive pressure. Such excessive pressure might occur if something solid and unyielding were to pass between the rolls, as, for example, if the feed spout 42 were to break off and be pulled into the rolls.

Casting downwardly at any angle below the horizontal has the advantage of facilitating the application of coolant water sprayed into the nip of the casting rolls as the cast metal exits. This effects faster cooling of the metal as it is cast, thereby speeding up the process considerably.

Another advantage is that the transverse feed box 54 can be left open at the top (or, if closed, viewing windows may be cut in the top) enabling the operator to observe the metal actually being cast, thereby giving him much finer control over the operation of the machine. I

Another advantage of downward casting is the fact that the machine can be stopped and started repeatedly without damage to or changing of the original feed nozzle. All that isnecessary is to shut off the flow of molten metal from the head box 46 into the nozzle, and then allow the molten metal in the feedspout to drain off into the rolls until empty, after which the machine can be stopped and started up again in the normal manner.

Still a further advantage of the invention is that the casting machine, as described, can be started and driven from a single drive line to one of the two casting rolls, therebytowing the other casting roll. This allows each casting roll to be ground as an individual roll instead of having to match grind them in pairs as is required of all existing operation casting machines, so as to obtain identical diameters.

Another embodiment of the invention is illustrated in FIG. 5, whichshows a continuous casting machine that is angularly adjustable so that the casting rolls can be positioned to cast at any angle, over a wide range. In this embodiment, the machine is designated in its entirety by the referencne numeral and those parts that are substantially the same as in the preceding embodiment are given the same reference numerals, with the prime suffix added.

Instead of having end frames 12 bolted down at one corner to the base plate the machine 10' is tiltably supported between two laterally spaced vertical posts 62 that extend upwardly from the base plate, the upper ends of which are provided with saddles 64 that receive the projecting ends of the roll necks 66 of the lower casting roll 17 The entire assembly, consisting of end frames 12' and rolls, is thus rotatable between the inclined position shown in solid lines, and the vertical or horizontal positions shown in phantom line outline. The machine is supported in the selected angular position by means of an adjustable strut 28', which operates in the manner of a turnbuckle. Strut 28 comprises two end yokes 70, one of which is connected by a pin bolt 72 to an ear 72 projecting upwardly from the base plate 25', while the other is connected by a pin bolt 73 to one edge of the frame member 30. The two end yokes have axially aligned, threaded shafts 74, the threads of which turn in opposite directions. Shafts 74 are screwed into opposite ends of a barrel 76, and the latter is adapted to be turned by means of a tool (not shown) to extend or shorten strut 28'. Changing the length of the strut causes the end frames 12' and associated structure to pivot about the axis of the lower casting roll 17', as shown. The feed spout (not shown) is articulated so as to follow the converging entrance to the space between the casting rolls as the upper casting roll moves along its arcuate path around the circumference of th lower casting roll. The use of a single drive shaft to drive only the lower casting roll 17' is particularly appropriate for this tiltable machine, as will be appreciated by those skilled in the art.

One of the advantageous features of mounting the end frames 12 for tilting movement about the axis of the lower casting roll 17 is that it enables the machine to be changed from an upwardly casting mode of oper ation to a downwardly casting mode, while it is running. There are certain advantages in being able to change from upwardly casting to downwardly casting, while the machine is in operation, chief of which is the fact that it is easier to start up the roll caster in the upwardly casting mode, whereas, a better cast product results when casting downwardly. The reason for this is as follows:

In starting up a roll caster, it is desirable to have the molten metal flow in an upward direction with a metal head not any higher than the highest point on the lower roll, or the centerline of the roll axes if casting vertically upward. This assures that only solidified metal will be carried through and beyond the bite of the rolls. If the roll speed is high enough, the emerging metal will not have time to completely solidify, but will be in a hot short" condition, producing what is called layover." In conventional casting practice, the caster is slowed down until a full sheet develops, and a production run then starts with no further alteration of the machine proper.

When casting downwardly, there is more difficulty in starting up, owing to trouble with runaway metal. Runaway metal is molten metal that breaks through the solidified shell of cast metal on the exit side of the rolls, which necessitates immediate shut-down of the apparatus. Start up with layover or hot short metal is impractical. These difficulties are much more pronounced with the more fluid molten metals. such as zinc alloys. With aluminum. start-ups can be made with preheated and dried pouring spouts, precise speed settings, and a metal dam used as a plug so a full sheet starts up at once. Once a successful start has been made, there are definite advantages in casting downwardly.

When casting upwardly after a start, the metal head can be increased somewhat to more completely fill shrinkage voids in the solidifying metal, but this is not as effective as in downward casting, where there is a natural tendency to feed the solidifying metal. This results in tighter cast metal. A side benefit is a reduction in the tendency to form a ripple surface pattern. Also, when casting upwardly, the pouring spout is at the bottom of the molten metal pool, whereas when casting downwardly, the spout is on the top of the pool, so there is a greater limitation on the amount the metal head can be raised when casting upwardly, as compared to downwardly, because of the limiting factor of flash-back around the pouring spout and its end dams.

Thus, the advantages of easier starting by casting upwardly at the start-up of the machine, together with sounder cast strip, increased productivity, and better surface quality achieved by casting downwardly once the machine has reached normal operating conditions, are realized in the present invention by providing a roll casting machine that can be changed over from upward casting (or horizontal casting) at the start-up, to downward casting once the machine has reached normal operating conditions. By tilting the machine about the axis of the bottom casting roll 17', it is possible to utilize a simple, straight-through drive from the driving motor to the lower casting roll, with the upper casting roll 16 being driven by friction of the cast metal product as it passes between the rolls.

While I have shown and described in considerable detail what I believe to be the preferred embodiments of the invention, it will be apparent to those skilled in the art that the invention is not limited to such details but might take various other forms.

I claim:

1. A continuous casting machine for producing wide sheet or plate, comprising:

a pair of parallel casting rolls spaced apart from one another to provide a space between them, said rolls having a relatively small diameter;

a feed spout connected to a source of molten metal, and having a nozzle extending into the converging space between said rolls from one side thereof, said spout having an internal passageway provided therein through which molten metal flows into the space between said rolls and said feed spout being shaped with cylindrically concave top and bottom surfaces that conform closely to the surfaces of the rolls with minimum clearance for friction-free operation, the relatively small diameter of said casting rolls giving said feed spout a blunt, wedgeshaped nozzle with ample thickness of material to resist pulling apart under working stresses; and

a pair of back-up rolls having rolling contact with said casting rolls on the sides of the latter opposite the area where the molten metal is delivered, said back-up rolls having the characteristics of extreme stiffness and rigidity, so as to reinforce said casting rolls and prevnet the latter from bowing apart under pressure of the solidified metal passing between the casting rolls; the assembly of casting rolls and back-up rolls being tiltable as a unit about a horizontal axis while the machine is in operation, so as to enable the machine to start up in the upwardly or horizontally casting mode, and then change over to downwardly casting.

2. A continuous casting machine as in claim 1, wherein said horizontal axis of tilting of the machine is the axis of the lower casting roll.

3. A continuous casting machine as in claim 2, wherein there is a driving connection solely to said lower casting roll, the upper casting roll being turned by frictional drag of the cast product as it is drawn through the casting rolls by the lower roll.

4. A continuous casting machine for producing sheet or plate, comprising:

a frame;

a pair of parallel casting rolls journaled on said frame, said rolls being spaced apart from one another to provide a space between them;

a feed spout connected to a souce of molten metal, and having a nozzle extending into the converging space between said rolls from one side thereof. said nozzle having an internal passageway provided therein through which molten metal flows into the space between the rolls;

said frame and casting rolls being tiltable as a unit about a horizontal axis while the machine is in operation, so as to enable the machine to start up in an upwardly or horizontally casting mode, and then change over to downwardly casting.

5. A continuous casting machine as in claim 4, wherein said horizontal axis of tilting of the machine is the axis of the lower casting roll.

6. A continuous casting machine as in claim 5, wherein there is a driving connection solely to said lower casting roll, the upper casting roll being turned by frictional drag of the cast product as it is drawn through the casting rolls by the lower roll.

I UNITED STATES PATENT OFFICE CERTIFICATE OF CORREQTWN Patent No. 3,817,317 Dated June 9 Inventor(s) OscaQrP. Gilmore It is certified that error appeers in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

In column 1,-line Z9, "sieres" should read -series--.

In column line 49, reierncne should read -referencero In column 5 ,-l'ine 68, "72" (first instance) should read --7l--.

In column 5, line 14 "th" should read -the--.

In column 8; line 4, "prevnet should read --pre/en't--.,

In column 8, line 26, "souce should read --s0urce.

Signed and sealed this lst day of October 1974,

(SEAL) Attest:

MCCOY M. GIBSON JR. I C. MARSHALL DANN Attesting Officer Commissioner of Patents FORM PO-105O (10-69] USCOMWDC 60376 P69 U.S. GOVERNMENT PRINTING OFFICE: I959 O366-334 

1. A continuous casting machine for producing wide sheet or plate, comprising: a pair of parallel casting rolls spaced apart from one another to provide a space between them, said rolls having a relatively small diameter; a feed spout connected to a source of molten metal, and having a nozzle extending into the converging space between said rolls from one side thereof, said spout having an internal passageway provided therein through which molten metal flows into the space between said rolls and said feed spout being shaped with cylindrically concave top and bottom surfaces that conform closely to the surfaces of the rolls with minimum clearance for friction-free operation, the relatively small diameter of said casting rolls giving said feed spout a blunt, wedge-shaped nozzle with ample thickness of material to resist pulling apart under working stresses; and a pair of back-up rolls having rolling contact with said casting rolls on the sides of the latter opposite the area where the molten metal is delivered, said back-up rolls having the characteristics of extreme stiffness and rigidity, so as to reinforce said casting rolls and prevnet the latter from bowing apart under pressure of the solidified metal passing between the casting rolls; the assembly of casting rolls and back-up rolls being tiltable as a unit about a horizontal axis while the machine is in operation, so as to enable the machine to start up in the upwardly or horizontally casting mode, and then change over to downwardly casting.
 2. A continuous casting machine as in claim 1, wherein said horizontal axis of tilting of the machine is the axis of the lower casting roll.
 3. A continuous casting machine as in claim 2, wherein there is a driving connection solely to said lower casting roll, the upper casting roll being turned by frictional drag of the cast product as it is drawn through the casting rolls by the lower roll.
 4. A continuous casting machine for producing sheet or plate, comprising: a frame; a pair of parallel casting rolls journaled on said frame, said rolls being spaced apart from one another to provide a space between them; a feed spout connected to a souce of molten metal, and having a nozzle extending into the converging space between said rolls from one side thereof, said nozzle having an internal passageway provided therein through which molten metal flows into the space between the rolls; said frame and casting rolls being tiltable as a unit about a horizontal axis while the machine is in operation, so as to enable the machine to start up in an upwardly or horizontally casting mode, and then change over to downwardly casting.
 5. A continuous casting machine as in claim 4, wherein said horizontal axis of tilting of the machine is the axis of the lower casting roll.
 6. A continuous casting machine as in claim 5, wherein there is a driving connection solely to said lower casting roll, the upper casting roll being turned by frictional drag of the cast product as it is drawn through the casting rolls by the lower roll. 